Protectors for electric circuits

ABSTRACT

An electric fuse has a cup-like housing that is subdivided into two separate compartments by a partition; and each compartment has a fusible element therein which is embedded within arcextinguishing material. A portion of the partition projects beyond the cup-like housing to enter a slot in a fuseholder to automatically align the terminals of the electric fuse with the fuse-receiving terminals of the fuseholder. An indicating lamp is connected in parallel with one of the fusible elements, and a second indicating lamp is connected in parallel with the other fusible element; and the conductors which connect those indicating lamps to the load terminals of the fuseholder are spaced far enough apart to prevent &#39;&#39;&#39;&#39;arc over&#39;&#39;&#39;&#39; but are close enough to each other to capacitively couple those lamps together in the event a transitory fault causes both of those fusible elements to blow and both of those lamps to become illuminated.

United States Patent 1191 Gaia et al.

[ Dec. 11, 1973 PROTECTORS FOR ELECTRIC CIRCUITS Primary ExaminerBernardA. Gilheany [75] Inventors: Aldino J. Gaia; Angelo Urani, both Ass'stamExammer F' Bell of St. Louis Mo AttorneyEdmund C. Rogers et al.

[73] Assignee: llficGraw-Edison Company, Elgin, 57 ABSTRACT I Anelectric fuse has a cup-like housing that is subdi- [22] Filed: Mar. 17,1972 vided into two separate compartments by a partition; I and eachcompartment has a fusible element therein [21] Appl' 235310 which isembedded within arc-extinguishing material. Related U.S. ApplicationData A portion of the partition projects beyond the cup-like 2 Divisionf Set 116,319 19, 1971, pat housing to enter a slot in a fuseholder toautomatically 3 739 313 align the terminals of the electric fuse withthe fusereceiving terminals of the fuseholder. An indicating [52] U.S.Cl 337/187, 337/189, 337/206, p is Connected in Parallel with One Of theusib e 337/265 elements, and a second indicating lamp is connected [51]Int. Cl. H0111 85/02 in parallel with the other fusible m an t [58]Field of Search 337/187, 188, 189, ductors which connect those n ng lmps to he 337/13 1 6 206 265 load terminals of the fuseholder are spacedfar enough apart to prevent arc over" but are close enough to [56]Referen e Cit d each other to capacitively couple those lamps togetherUNITED STATES PATENTS in the event a transitory fault causes both ofthose fusible elements to blow and both of those lamps to be- 2,4l7,6923/1947 Kline 337/188 3,139,499 6/1964 Cosgrove 337/188 mummated 11Claims, 13 Drawing Figures J, 236 /2# y 1 2, 202 /f6 236 8 /72 2/4 36-42/4 /20 20 ZZ@ Z20 6* 20? 4 0 lzaz 72 PAIENTEUBEBI 1 I913 5718.140

I SHEET 1 0F 2 FIG' 2 PROTECTORS FOR ELECTRIC CIRCUITS This is adivision of application Ser. No. 116,819 filed Feb. 19, 1971, now US.Pat. No. 3,739,313.

This invention relates to improvements in Protectors For ElectricCircuits. More particularly, this invention relates to improvements inelectric fuses and fuseholders therefor.

It is, therefore, an object of the present invention to provide animproved electric fuse and an improved fuseholder therefor.

The electric fuse provided by the present invention has a cup-likehousing that is subdivided into two separate compartments by apartition; and each compartment has a fusible element therein which isembedded within arc-extinguishing material. That partition will keepmetal vapors, that may form as one or the other of the fusible elementsblows, from passing into the other compartment. A portion of thepartition projects beyond the cup-like housing to enter a slot in afuseholder to automatically align the terminals of the electric fusewith the fuse-receiving terminals of the fuseholder. As a result, thepartition of the electric fuse provided by the present inventionperforms a dual function namely, it subdivides the housing into twoseparate compartments, and it automatically aligns the terminals of theelectric fuse with the fuse-receiving terminals of a fuse-holder. It is,therefore, an object of the present invention to provide an electricfuse with a partition which subdivides the cup-like housing of thatelectric fuse into two separate compartments and which also acts as analigning blade.

The cup-like housing of the electric fuse provided by the presentinvention is closed by a closure which has a slot therein thataccommodates that part of the partition which acts as an aligning blade;and portions of that partition underlie portions of that closure.Sealing material seals the joint between the aligning blade and the slotin the closure, and further sealing material seals the periphery of theclosure to the cup-like housing. As a result, that cup-like housing canprevent any loss of the arc-extinguishing material therein; and it alsocan prevent the escape therefrom of any metal vapors that develop as afusible element, within that cup-like housing, fuses. It is, therefore,an object of the present invention to provide the closure of a cup-likehousing of an electric fuse with a slot that accommodates, and that canbe sealed to, the aligning blade of that cup-like housing.

The fuseholder of the present invention has L-shaped line terminals andhas L-shaped load terminals. The feet of the line terminals confront andextend toward each other, and thus space the remaining portions of thoseline terminals apart appreciable distances. The feet of the loadterminals confront and extend toward each other, and thus space theremaining portions of those load terminals apart appreciable distances.The feet of the line and load terminals are connected to thefuse-receiving terminals of the fuseholder; and hence the remainingportions of those line and load terminals are spaced further apart thanare those fuse-receiving terminals. It is, therefore, an object of thepresent invention to provide a fuseholder with L-shaped line and loadterminals that have the feet thereof confronting and extending towardeach other and that are connected to the fuse-receiving terminals of thefuseholder.

The fuseholder of the present invention has an externally threaded bossthat has fuse-receiving terminals therein, has a second boss that isdisplaced from that externally threaded boss, has an indicating lamp inregister with an opening in that second boss, and has a nut that coactswith the externally threaded boss to hold the fuseholder in assembledrelation with a panel. That panel has an opening which accommodates theexternally threaded boss and has a second opening which accommodates thesecond boss. A fuse, at the front side of the panel, will have theterminals thereof held by the fuse-receiving terminals in the externallythreaded boss; and the blowing of that fuse will be readily apparcutbecause light will pass forwardly from the indicating lamp through theopening in the second boss.

In many installations where electric fuses are used, it is desirablethat a neon lamp glow continuously subsequent to the blowing of a fuse;and, in recognition of that fact, fuseholders have been proposed whichwould illuminate a neon lamp whenever a fuse therein opened apower-supplying circuit. Where a fuse opens a power supplying circuit inresponse to a fault that is of a continuing nature, that fault canestablish and maintain an indicating circuit which includes the neonlamp, and thus can keep that neon lamp glowing continuously. However, ifthe fault which causes the fuse to open the power-supplying circuit isof a transitory nature, that fault can establish an indicating circuitthat will illuminate the neon lamp, but that fault will be incapable ofmaintaining that indicating circuit and thus will be incapable of makingcertain that the neon lamp continues to glow. In some cases, theelongated conductors which extend from the fuse panel to the load arelong enough, and are in such close proximity to each other, that theycan act as the plates of a capacitor; and thus can keep the neon lamp ofan indicating circuit flowing even though the fault which blew the fuseand illuminated the neon lamp subsequently clears. In certaininstallations, however, the lengths and placements of the conductors,which extend between the fuse panel and the load, can not be relied uponto provide sufficient capacitance to keep the neon lamp of an indicatingcircuit glowing after the fault has cleared. Consequently, it would bedesirable to provide a fuseholder which could assure continuedenergization of a neon lamp even where the fault, that caused theelectric fuse in that fuseholder to blow, was of short duration. Thepresent invention provides such a fuseholder; and it does so by mountingwithin that fuseholder conductors which are interposed between theelectric fuse and the load terminals of that fuseholder and which areclose enough to each other to act as a capacitor and thereby maintain aneon lamp aglow after a fault, of temporary nature, has blown theelectric fuse and has initiated the glowing of that neon lamp. It is,therefore, an object of the present invention to provide a fuseholderwhich has conductors intermediate the electric fuse and the loadterminals and which are so close to each other that they can act as theplates of a capacitor, and can thus keep an indicating neon lamp glowingafter a fault of short duration has blown the fuse and has illuminatedthat neon lamp.

The electric fuse provided by the present invention has a circuitboard-on which the conductors between the fuse terminals and the loadterminals are formed. As a result, the spacing between those conductorscan be precisely determined and continuously maintained.

The circuit board of the fuseholder provided by the present inventionalso has an indicating lamp thereon; and, in addition, has a pinadjacent that indicating lamp. The fuseholder has a recess whichaccommodates the indicating lamp, and also has a small-diameter socketwhich receives the pin adjacent that indicating lamp. The pin on thecircuit board and the socket for that pin will align the indicating lampwith the recess therefor in the fuseholder; and the positioning of thatpin within that socket will prevent appreciable shifting of thatindicating lamp relative to the recess therefor. The lamp-receivingrecess has a window therein, and the engagement between the pin on thecircuit board and the socket in the fuseholder will hold the indicatinglamp in register with the window in that recess.

Other and further objects and advantages of the present invention shouldbecome apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description, a preferred embodiment ofthe present invention is shown and described, but it is to be understoodthat the drawing and accompanying description are for the purpose ofillustration only and do not limit the invention and that the inventionwill be defined by the appended claims.

In the drawing, FIG. 1 is a front elevational view of preferredembodiments of a fuseholder and electric fuse that are made inaccordance with the principles and teachings of the present invention,

FIG. 2 is a sectional view, on a larger scale, through the fuseholder ofFIG. 1, and it is taken along the plane indicated by the line 2-2 inFIG. 1,

FIG. 3 is a sectional view, on the scale of FIG. 2, through the electricfuse and fuseholder of FIG. l, and it is taken along the plane indicatedby the line 3-3 in FIG. 1,

FIG. 4 is a sectional view, on the scale of FIG. 2, through the electricfuse and fuseholder of FIG. I, and it is taken along the plane indicatedby the line 44 in FIG. 1,

FIG. 5 is a partially broken-away rear view, on the scale of FIG. 1, ofthe fuseholder shown in FIG. ll,

FIG. 6 isa sectional view, on the scale of FIG. ll, through thefuseholder of FIG. I, and it is taken along the plane indicated by theline 66 in FIG. 5,

FIG. 7 is a sectional view, on the scale of FIG. 2, through the electricfuse and fuseholder of FIG. I, and it is taken along the broken planeindicated by the broken line 7-7 in FIG. 5,

FIG. 8 is an exploded view of the fuseholder of FIG. 1,

FIG. 9 is an exploded view of the electric fuse of FIG.

FIG. 10 is a perspective view of the circuit board for the fuseholder ofFIG. 1,

FIG. 11 is a perspective view of part of the electric fuse shown in FIG.1,

FIG. 12 is an end view of the aligning blade of the electric fuse ofFIG. 1, and it shows by dotted lines how that aligning blade could bemade with different widths, and

FIG. 13 is an end view of the aligning blade of the electric fuse ofFIG. 1, and it shows by dotted lines how that aligning blade could bemade with different thicknesses.

Referring to the drawing in detail, the numeral 20 generally denotes apreferred embodiment of fuseholder that is made in accordance with theprinciples and teachings of the present invention; and that fuseholderhas an externally threaded boss 22. Four shouldered recesses 24, 26, 28and 30 are formed in the boss 22; and each of those shouldered recesseshas a relatively large diameter portion that opens to the front surfaceof that boss and has a smaller-diameter portion that opens to the rearsurface of the fuseholder 20. A slot 32 is formed in the boss 22, asshown particularly by FIG. 8; and that slot extends an appreciabledistance inwardly of the front surface of that boss, as shownparticularly by FIG. 7. An annular recess 34 is formed in the frontsurface of the boss 22, as shown particularly by FIGS. 7 and 8. Theouter diameter of the annular recess 34 is slightly smaller than theroot diameter of the external thread on the boss 22.

A generally L-shaped recess 36 is formed in the rear face of thefuseholder 20; and that recess communicates with the shouldered recess26. A generally L- shaped recess 38 is formed in the rear face of thefuseholder 20; and that recess communicates with the shouldered recess24. A short, transversely directed recess 40 is formed in the rear faceof the fuseholder 20; and that recess communicates with the shoulderedrecess 28. A short, transversely directed recess 42 is formed in therear face of the fuseholder 20; and that recess communicates with theshouldered recess 30. A partition 44, which is shown particularly inFIG. 4, is provided between the L-shaped recess 36 and the short,transversely directed recess 40. As shown particularly by FIG. 6, thepartition 44 also extends between the L-shaped recess 38 and the short,transversely directed recess 42. A partition 46 is displaced from thepartition 44 by and one end of the partition 46 separates portions ofthe L-shaped recesses 36 and 3:8, as shown by FIG. 7, while the otherend of that partition separates portions of the short, transverselydirected recesses 40 and 42, as shown by FIG. 5.

A relatively large, rectangular recess 48 is formed in the rear face ofthe fuseholder 20; and part of that recess underlies a shallowcylindrical boss 56 that projects forwardly from the front surface ofthat fuseholder. A smaller but deeper rectangular recess 50 directlyunderlies the boss 56; and the rear of that recess is in communicationwith'the recess 48, as shown by FIG. 3. A small diameter, cylindricalsocket 52 is provided in the boss 56; and that socket extends from theforward surface of that boss to the recess 48, as shown by FIG. 3. Asmall diameter, cylindrical socket 54 also is formed in the boss 56; andthat socket also extends from the forward surface of that boss to therecess 48, as shown by FIG. 3. Circular openings 58 and 60 are formed inthe front surface of the boss 56; and a transparent plate 62 is disposedwithin the recess 50 immediately adjacent the openings 58 and 60 thattransparent plate serving as windows for those openings. A transparentsealing material, now shown, is disposed within the openings 58 and 60to coact with the transparent plate 62 to provide a water-tight closingof those openings. A raised arrow 64 is formed on the forward face ofthe boss 56 adjacent the cylindrical socket 54; and a raised arrow 66 isformed on that forward face adjacent the cylindrical socket 52. Asindicated particularly by FIGS. 1 and 8, the raised arrow 66 points tothe left, and thus generally toward the opening 60; whereas the raisedarrow 64 points to the right, and thus generally toward the opening 58.An opening 68 is provided in the fuseholder 20 adjacent one side of thatfuseholder, as shown particularly by FIGS. 5 and 7. A similar opening,not shown, is provided in the fuseholder adjacent the opposite side ofthat fuseholder.

The numeral 69 denotes a notch at one side of the rear face of thefuseholder 20, and the numeral 71 denotes a notch at the opposite sideof that rear face; all as indicated by FIG. 5. The numerals 73 and 75denote notches at one end of the rear face of the fuseholder 20, asindicated by FIG. 8.

The numeral 72 denotes an O-ring which is disposed within the annularrecess 34 in the forward surface of the boss 22. That O-ring is circularin cross section; and the normal, unstressed diameter of a circularcross section of that O-ring is greater than the depth of the annularrecess 34. As a result, whenever the O-ring 72 is in its unstressedcondition, the outer face of that O-ring will project outwardly beyondthe outer face of the boss 22 of the fuseholder 20.

The numeral 74 denotes a shouldered conductor which is disposed withinthe shouldered recess 26 in the fuseholder 20. Thelarge diameter portionof the shouldered recess 26 accommodates a tulip-type socket in thelarge diameter end of the conductor 74, the smaller diameter portion ofthe shouldered recess 26 accommodates an intermediate-diameter portionof the conductor 74, and a small diameter end portion of that conductorprojects rearwardly beyond the recess 36. The numerals 76, 78 and 80denote conductors which are identical to the conductor 74; but thoseconductors are disposed, respectively, within the shouldered recesses28, 30 and 24 of the fuseholder 20. A generally L- shaped conductor 82has an opening 84 in the foot thereof which receives theintermediate-diameter portion of the conductor 80, as shown particularlyby FIG. 7. The L-shaped conductor 82 has a reduced-width portion 86adjacent the outer end thereof, and it has an offset 87 intermediate theopening 84 and the reducedwidth portion 86; all as shown by FIG. 8. Theouter end of the L-shaped conductor 82 extends through the notch 73 inthe rear face of the fuseholder 20. The numeral 88 denotes an L-shapedconductor which is the mirror image of the L-shaped conductor 82. Theopening 90 in the foot of the L-shaped conductor 88 receives theintermediate-diameter portion of the conductor 74, as shown by FIG. 7.The L-shaped conductor 88 has a reduced-width portion 92 adjacent theouter end thereof, and it has an offset 93 between that reduced-widthportion and the opening 90; all as shown by FIG. 8. The outer end of theL-shaped conductor 88 extends through the notch 75 in the rear face ofthe fuseholder 20. The numeral 94 denotes a wire-securing connectorwhich is mounted on the reduced-width portion 86 of the L-shapedconductor 82', and the numeral 96 denotes a wire-securing connectorwhich is mounted on the reduced-width portion 92 of the L- shapedconductor 88.

The numeral 98 denotes an L-shaped conductor which has an opening 100 inthe foot thereof; and that opening accommodates theintermediate-diameter portion of conductor 78. The outer end of theL-shaped conductor 98 has a threaded opening 102 therein which receivesthe shank ofa screw 104. A lock washer 106 will be telescoped over theshank of that screw before that shank is threaded into the opening 102.An offset 107 is provided intermediate the openings 100 and 102 in theL-shaped conductor 98. The numeral 108 denotes an L-shaped conductorwhich is the mirror image of the L-shaped conductor 98. An opening 110in the foot of the L-shaped conductor 108 accommodates theintermediate-diameter portion of the conductor 76. A threaded opening111 in the outer end of the L-shaped conductor 108 accommodates theshank of a screw 112; and that shank will pass through a lock washerbefore it is seated in the threaded opening 111. An offset 113 isprovided in the L-shaped conductor 108 intermediate the openings 110 and111.

The numeral 114 denotes a rivet which is mounted within the opening 68in the fuseholder 20. A similar rivet, not shown, is disposed within theopening in the opposite side of the fuseholder 20. The numeral 118denotes a gasket which is generally rectangular in configuration, whichhas an opening that encircles and closely fits the externally threadedboss 22, and which has a second opening that encircles and closely fitsthe boss 56. As indicated particularly by FIGS. 1 and 8, the dimensionsof the gasket 118 are just slightly smaller than the dimensions of thefuseholder 20.

The numeral 120 denotes a circuit board which is made of insulatingmaterial; and that circuit board is provided with openings 122 and 124to accommodate shouldered pins 154 and 156, respectively, as shown byFIG. 3. The openings 122 and 124, and the shouldered pins 154 and 156held thereby, are in register with the sockets 52 and 54 in the boss 56.The circuit board 120 also has openings 126 and 128 which accommodatethe rear ends of the glass envelopes for neon lamps 158 and 160,respectively, as shown in FIG. 2. The circuit board 120 has openings 130and 132 for leads of the neon lamps 158 and 160, respectively, as shownby FIG. 8; and the circuit board 120 has openings 134 and 136 forterminals of resistors 166 and 170, as indicated by FIG. 8. The circuitboard has oenings 138, 140, 142 and 144 to accommodate thesmall-diameter ends of conductors 80, 74, 78 and 76, respectively.

Conductors 146, 148, 150 and 152 are provided on the rear surface of thecircuit board 120, as shown by FIGS. 5 and 10. A mass of solder 162connects one lead of the lamp 158 to the conductor 152; and a mass ofsolder 180 connects the other end of that conductor to thesmall-diameter end of conductor 78 which is disposed within the opening142 in the circuit board 120. A mass of solder 164 connects one end ofthe conductor 146 to one terminal of the lamp 160; and a mass of solder178 connects the other end of that conductor to the small diameter endof the conductor 76 which is disposed within the opening 144 in thecircuit board 120. The conductor 148 extends from the shouldered pin 154to the small diameter end of the conductor 74, which is disposed withinthe opening in the circuit board 120; and a mass of solder 176electrically connects the conductor 148 to the small diameter end ofconductor 74 and also to one terminal of resistor 170. The otherterminal of that resistor is connected to the other terminal of the lamp160; and a sleeve 172 of insulation encases and protects thatconnection. The conductor extends from the shouldered pin 156 to thesmall diameter end of the conductor 80 which is disposed within theopening 138 in the circuit board 120; and a mass of solder 174electrically connects the conductor 150 to the small diameter end ofconductor 80 and also to one terminal of resistor 166. The otherterminal of that resistor is connected to the other termiha] of the lamp158; and a sleeve 168 of insulation encases and protects thatconnection.

The circuit board 120 and the conductors 146, 148, 150 and 152 thereoncan be made in different ways, as desired. Preferably, however, thatcircuit board and those conductors are made by use of printed circuitboard techniques starting with a metal-clad sheet of insulation, usingacid-resistant ink to print a pattern on the metal layer of that sheetwhich is identical to the conductors 146, 148, 150 and 152, and thenetching away the rest of that metal layer. As a result, the circuitboard 120 can be considered to be a printed circuit board.

The numeral 182 denotes a closure which is intended to underlie and toclose the rear face of the fuseholder 20. That closure has a raisedsurface 184 which confronts and is close to the rear face of the circuitboard 120. Elongated bosses 186 and 188 project forwardly beyond theraised surface 184', and those bosses will be disposed within thenotches 69 and 71, respectively, at the sides of the rearface of thefuseholder 20. A shouldered passage 190 is formed in the boss 186; andthat passage accommodates one end of the rivet 114. As shownparticularly by FIG. 7, the rivet 114 will coact with the shoulderedpassage 190 to help hold the closure 182 in assembled relation with thefuseholder 20. A shouldered passage 192 is provided in the boss 188; andthat shouldered passage will receive one end of a rivet, not shown,which is similar to the rivet 114. A suitable sealing material 193 fillsand seals the exposed end of the shouldered passage 192, as shown byFIG. 5. Similar sealing material, shown in FIG. 7, will be used to filland seal the exposed end of the passage 190. Elongated ribs 194 and 196are provided at the rear face of the closure 182; and those ribs areparallel to the sides of the fuseholder 20. One end of the closure 182is cut away to define notches 195 and 197; and the notch 195 will exposethe screw 104 while the notch 197 will expose the screw 112, when thatclosure is assembled with the rear face of the fuseholder 20.

The numeral 198 generally denotes an electric fuse which has a generallycup-like housing 200 with an outwardly extending annular flange 202adjacent the open end thereof, as shown by FIG. 8. The housing 200 has ashallow cylindrical recess'204 in the outer face of the closed endthereof; and an indicia-bearing disc, not shown, can be disposed andheld within that recess. That disc could bear the voltage rating and theampere rating of that electric fuse. The housing 200 has a partition 206therein; and that partition subdivides the interior of that housing intotwo separate compartments. In addition, one portion of the partition 206projects outwardly beyond the open end of the housing 200, as shownparticularly by FIG. 9, to constitute an aligning blade. An annularrecess 208 is provided inwardly of the outwardly extending annularflange 202, as shown by FIG. 9. The portion of the partition 206 whichextends between the annular recess 208 and the inner end of the housing200 has a width that is equal to the inner diameter of that housing; butthe portion of that partition which projects outwardly through andbeyond the annular recess 208 has a reduced width, as shown particularlyby FIGS. 3 and 9.

A disc-like support 210 of insulating material has a slot 212 thereinwhich is dimensioned to accommodate the outwardly extending portion ofthe partition 206 of the housing 200. The support 212 is dimensioned totit neatly within the annular recess 208 in the housing 200. Shoulderedpins 214, 216, 218 and 220 are fixedly mounted within four openings inthe support 210; and one end of the pin 216 is dimensioned to extendwithin and to be tightly gripped by the tulip-type socket in the outerend of the conductor 80. The pins 214, 218, and 220 are dimensioned tohave the outer ends thereof extend within and to be tightly gripped bythe tulip-type sockets in the outer end of conductors 74, 78 and 76,respectively. An opening 222 is formed in the support 210 intermediatethe pins 214 and 220; and an opening 224 is formed in that supportintermediate the pins 216 and 218. A fusible element 226 is suitablysecured to the inner ends of the pins 216 and 218; and a fusible element228 is suitably secured to the inner ends of the pins 214 and 220. Theinner ends of the pins 214, 216, 218 and 220 are dimensioned to hold thefusible elements 226 and 228 within the two compartments defined withinthe housing 200 by the partition 206, and to hold those fusible elementsin spaced relation to the inner surfaces of those compartments.Arc-quenching material 230 is provided within the two compartments inthe housing 200 to quickly quench any arc which forms as either of thefusible elements 226 and 228 fuses.

Sealing material 233 is placed in the openings 222 and 224 to close andseal those openings after the arcquenching material has been introducedinto the two compartments of the housing 200 via those openings. Inaddition, sealing material 231 is used to close and seal the jointbetween the slot 212 in support 210 and the aligning portion ofpartition 206; and further sealing material 231 is used to close andseal the joint between the periphery of support 210 and the annularrecess 208 in the housing 200. That sealing material will coact withthat housing, with that partition, and with that support to prevent anyleakage of arc-quenching material and to prevent any escape of vaporswhich develop as one or both of the fusible elements 226 and 228 fuses.

The numeral 232 denotes a nut which has an internal thread that can matewith the external thread on the boss 22. A knurled nut 234 also has aninternal thread which can mate with the external thread on the boss 22;and that knurled nut has an inwardly-extending annular flange 236. Theinner diameter of the annular flange 236 is larger than the principaldiameter of the housing 200 of the electric fuse 198, but is smallerthan the outer diameter of the outwardly extending annular .flange 202on that housing. As a result, the knurled nut 234 can hold the electricfuse 198 in assembled relation with the fuseholder 20.

The feet and the forwardly offset portions of the L- shaped conductors82, 88, 98 and 108 are disposed within and are quided by the recesses38, 36, 42 and 40, respectively, in the rear face of the fuseholder 20.The rearwardly-offset outer ends of the L-shaped conductors 82 and 88constitute the line terminals of the fuseholder 20; and the rearwardlyoffset portions of the L-shaped conductors 98 and 108 constitute theload terminals of that fuseholder. The mass of solder which surroundsthe opening 84 in the foot of the L-shaped conductor 82 electricallybonds and mechanically secures that L-shaped conductor to the conductor80, and also mechanically secures both of those conductors to thefuseholder 20. Similarly, the masses of solder which surround theopenings 90, and 110, respectively, in the L-shaped conductors 88, 98and 108 electrically bond and mechanically secure those L-shapedconductors to the conductors 74, 78 and 76, respectively. Further, thosemasses of solder mechanically secure the L-shaped conductors 88, 98, and108 and the conductors 74, 78 and 76 to the fuseholder 20. The masses ofsolder 174, 176, 178 and 180 electrically bond conductor 150 toconductor 80, electrically bond conductor 148 to conductor 74,electrically bond conductor 146 to conductor 76, and electrically bondconductor 152 to conductor 78. In addition, the masses of solder 174,176, 178 and 180 mechanically secure the circuit board 120 to thefuseholder 20. The shouldered pins 154 and 156 will coact with thesockets 52 and 54 in the boss 56 to hold the neon lamps 158 and 160,respectively, in register with the openings 60 and 58 in that boss.

In the preferred embodiments of fuseholder and electric fuse shown inthe drawing, the conductors 74, 76, 78 and 80 are oriented and spaced todefine a square; and the pins 214, 220, 218 and 216 of the electric fuse198 are oriented and spaced to define a congruent square. Manufacturingtolerances will, however, keep the orientation and spacing of the pins214, 220, 218 and 216 from being exactly congruent to the orientationand spacing of the conductors 74, 76, 78 and 80; and this is desirable,because it will increase the contact pressures between those pins andthose conductors. Specifically, if manufacturing tolerances cause theaxes of the pins 214 and 216 to be spaced further apart than the axes ofthe conductors 74 and 80, those pins will apply forces to the tulip-typesockets in the forward ends of those conductors which will tend to forcethe more remotely-located fingers of those tulip-type sockets apart witha force that is greater than normal. The shouldered recesses 26 and 24closely encircle the fingers of the tulip-type sockets in the forwardends of the conductors 74 and 80; and that close encircling plus therestorative forces within those fingers will enable those fingers toapply substantial contact pressures to the pins 214 and 216. Conversely,if manufacturing tolerances cause the axes of the pins 214 and 216 to bespaced closer together than the axes of the conductors 74 and 80, thosepins will apply forces to the tulip-type sockets in the forward ends'ofthose conductors which will tend to force the more closely locatedfingers of those tulip-type sockets apart with a force that is greaterthan normal. The close encircling, by the shouldered recesses 26 and 24,of the fingers of the tuliptype sockets in the forward ends of theconductors 74 and 80 will coact with the restorative forces within thefingers of those conductors to enable those fingers to apply substantialcontact pressures to the pins 214 and 216. Similarly, any increases ordecreases in the spacings between the axes of the pins 214, 216, 218 and220, due to manufacturing tolerances, and any increases or decreases inthe spacings between the axes of the conductors 74, 80, 78 and 76, dueto manufacturing tolerances, will tend to increase the contact pressuresbetween those pins and those conductors. Those increases and decreasesin the spacings between the axes of the pins 214, 216, 218 and 220, andthose increases and decreases in the spacings between the axes of theconductors 74, 80, 78 and 76, can be along any of the sides ofthe squaredefined by those pins and also can be along either of the diagonals ofthat square. Consequently, the manufacturing tolerances of those fourpins, of those four conductors, of the support 210, and of theexternally threaded boss 22 will make certain that higher-than normalcontact pressures will be established and maintained between those pinsand those conductors. Such higher than normal contact pressures aredesirable, because they increase the current-carrying capability of thecombination of fuseholder and electric fuse. All of this means that byproviding four fuse terminals on the electric fuse 198 and by providingfour complementary fuse-receiving terminals on the fuseholder 20, thepresent invention enables manufacturing tolerances to effect thedevelopment of positive laterally-directed and longitudinally directedforces which develop higher-than normal contact pressures between thoseterminals.

Whenever the fuse 198 is assembled with the fuseholder 20, the lineterminals 82 and 88 are connected to line, and the load terminals 98 and108 are connected to a load, current will flow via line terminal 82,conductor 80, pin 216, fusible element 226, pin 218, conductor 78, loadterminal 98, a conductor, not shown, extending to the load, a furtherconductor, not shown, extending from the load to load terminal 108,conductor 76, pin 220, fusible element 228, pin 214, and line terminal88. Essentially no current will flow from conductor via conductor 150,resistor 166, lamp 158, and conductor 152 to conductor 78; because theresistance of the fusible element 226 is so very much smaller than thecombined resistances of resistor 166 and lamp 158. Similarly,essentially no current will flow from conductor 74 via conductor 148,resistor 170, lamp 160, and conductor 146 to conductor 76; because theresistance of the fusible element 228 is so very much smaller than thecombined resistances of resistor 170 and lamp 160. As a result, thelamps 158 and 160 will normally remain unilluminated, and no light willbe visible through the openings 60 and 58 in the boss 56.

In the event a fault develops in the load, not shown, or between theconductors, not shown, which are connected to the load terminals 98 and108, either or both of the fusible elements 226 and 228 may fuse. If thefusible element 226 fuses, but the fusible element 228 remains intact,current will flow from line terminal 82 via conductor 80, conductor 150,resistor 166, lamp 158, conductor 152, and conductor 78 to the loadterminal 98; and that flow of current will illuminate that lamp. As longas the fusible element 228 remains intact, essentially no current willflow through resistor and lamp 160; and hence that lamp will remainunilluminated. The light passing outwardly through the opening 60 in theboss 56 will pass through the opening in the panel, not shown, in whichthat boss is mounted; and that light will plainly indicate to themaintenance man that the fusible element 226 has blown. The maintenanceman will, thereupon, rotate the knurled nut 234 in the counter-clockwisedirection in FIG. 8, and

thereby remove that nut from the externally threaded boss 22 whichextends through a second opening in the panel, not shown. At such time,the maintenance man can apply an outwardly directed pull to the housing200 of the electric fuse 198, and thereby separate that electric fusefrom the fuseholder 20. A replacement fuse can then have the terminals214, 216, 218 and 220 thereof aligned, respectively, with the conductors74, 80, 78 and 76 of the fuseholder 20; and the aligning portion of thepartition 206 of that replacement fuse will coact with the slot 32 inthe externally threaded boss 22 to insure that alignment. Specifically,the portion of the partition 206 which projects outwardly beyond theannular recess 208 in the housing 200 of the replacement fuse will belonger than the portions of the pins 214, 216, 218 and 220 which projectoutwardly from the support 210 of that fuse; and hence that portion ofthat partition will have to be aligned with, and will have to enter, theslot 32 before any of those pins can begin to enter. the tulip-typesockets therefor. As the replacement electric fuse is pressed intoengagement with the fuseholder 20, it will apply force to thatfuseholder which will tend to move that fuseholder rearwardly and awayfrom the panel, not shown. However, the nut 232 will be solidly seatedon the externally threaded boss 22 of that fuseholder, and will thusprevent any such rearward movement. Once the terminals 214, 216, 218 and220 of the replacement electric fuse have been seated, respectively,within the tulip-type sockets in the forward ends of the conductors 74,80, 78 and 76, the knurled nut 234 will again be threaded onto theexternally threaded boss 22. The annular flange 236 of that knurled nutwill overlie the outwardly extending flange 202 on the housing 200 ofthe replacement electric fuse; and thus will thereby positively preventaccidental separation of that replacement electric fuse from thefuseholder 20.

At the time the fusible element 236 fused, flame and metal vapors mayhave been evolved; but that flame and those metal vapors could notescape from the housing 200 of the electric fuse 198. Specifically, thesealing material within the opening 224, the sealing material 231 in thejoint between the projecting portion of the partition 206 and the slot212 in the support 210, and the sealing material 231 which seals thecircular joint between the periphery of the support 210 and the annularrecess 208 in the housing 200 will effectively prevent any escape offlame or metal vapors. The user of the electric fuse and fuseholderprovided by the present invention can be assured that the sealingmaterial in the opening 224 and the sealing material 233 in the opening222 will not be broken by nearby objects; because those openings aredisposed, respectively, between the pins 216 and 218 and between thepins 214 and 220. Those pins will project outwardly from the support210, and will thereby keep any nearby objects from contacting andinjuring the sealing material within the openings 224 and 222. The closeproximity of the support 210 to the forward face of the externallythreaded boss 22, whenever the electric fuse 198 is assembled with thefuseholder 20, and the fact that the O-ring 72 is disposed outwardly ofand surrounds the circular joint between the support 210 and the annularrecess 208 in the housing 200, will make certain that the said circularjoint is protected from nearby objects whenever the electric fuse 198 isin assembled relation with the fuseholder 20. In addition, the knurlednut 234 will provide additional protection for the sealing material inthe circular joint between the support 210 and the annular recess 208 inthe housing 200, whenever the electric fuse 198 is assembled with thefuseholder and that knurled nut is holding that electric fuse and thatfuseholder in such relation.

If the fusible element 228, rather than the fusible element 226, hadblown in response to the fault which developed in the load, or in one orboth of the conductors connected to the load terminals 98 and 108, thelamp 160, rather than the lamp 158, would have become illuminated. Lightfrom the lamp would then pass 0utwardly through the opening 58 in theboss 56 and would pass through the opening in the panel, not shown, inwhich that boss is mounted. That light would plainly indicate to themaintenance man that the fusible element 228 had blown. The maintenanceman would then replace the electric fuse 198.

If the fault in the load, or in the conductors connected to the loadterminals 98 and 108, had caused both of the fusible elements 226 and228 to blow, both of the lamps 158 and 160 would have becomeilluminated. As long as that fault persisted, current would flow fromline terminal 82 via conductor 80, conductor 150, resistor 166, lamp158, conductor 152, conductor 78, load terminal 98, the conductorconnected between that load terminal and the fault, through the fault tothe conductor connected to the load terminal 108, and then via conductor76, conductor 146, lamp 160, resistor 170, conductor 148, conductor 74,and line terminal 88. The values of the resistors 166 and 170 are highenough so those resistors will protect the lamps 158 and 160 in theevent only one of those lamps becomes illuminated; but those values arelow enough to enable both of those lamps to become illuminated wheneverboth of the fusible elements 226 and 228 blow.

In the event a fault which causes both of the fusible elements 226 and228 to blow is of a transitory nature, and disappears after it has blownthose fusible elements and has caused both of the lamps 158 and 160 tobecome illuminated, that fault will be unable to maintain the circuitwhich illuminated those lamps. However, those lamps will continue toremain illuminated because of a capacitive effect which is provided bythe closely spaced upper ends of conductors 146 and 152, as thoseconductors are viewed in FIGS. 5 and 10. The spacing between those endsis great enough to prevent arcing over, but is small enough to provide acapacitance which will keep the lamps 158 and 160 illuminated after atransitory fault has caused both of the fusible elements 226 and 228 toblow and hascaused those lamps to become illuminated. This is highlydesirable; because it makes certain that the lamps 158 and 160 willremain illuminated, and will thus indicate that a fault occurred, evenif that fault subsequently disappearsv It will be noted that the outerends of the line terminals 82 and 88 are spaced further apart than arethe conductors 80 and 74; and it also will be noted that the outer endsof the load terminals 98 and 108 are spaced further apart than are theconductors 78 and 76. This is desirable because it will minimize thelikelihood of any arcing over between conductors connected to the lineterminals 82 and 88, and also will minimize the likelihood of any arcingover between conductors connected to the load terminals 98 and 108.

The electric fuse 198 andthe fuseholder 20 provided by the presentinvention can be arranged to prevent the substitution of an electricfuse of an undesired ampere rating for an electric fuse of a desiredampere rating. Specifically, as shown by FIG. 12, the portion of thepartition 206 which acts as an aligning blade can be made in differentwidths; and the slot 32 in the externally threaded boss 22 can be madein different lengths. To prevent over fusing, the smallest ampere-ratingfuse to be used with the fuseholder 20 should have the narrowestaligning blade, the largest ampere-rating fuse should have the widestaligning blade, and electric fuses with intermediate ampere ratingsshould have aligning blades of widths intermediate those of the widestand narrowest aligning blades. The externallythreaded boss 22 shouldhave a slot 32 with a width that would correspond to the width of thealigning blade of the fuse having the desired ampere rating; and no fusehaving a larger ampere rating could then be inserted in that Slot.

As indicated particularly by FIG. 13, the aligning portion of thepartition 206 of the electric fuse 198 can be given differentthicknesses, and the slot 32 in the externally threaded boss 22 of thefuseholder can be provided with corresponding thicknesses. Specifically,the smallest ampere-rating electric fuse to be used with the fuseholder20 should have the thinnest partition 206, and progressively largerampere-rating fuses should have progressively thicker aligning blades.The externally threaded boss 22 should have a slot 32 with a thicknessthat would correspond to the thickness of the aligning blade of the fusehaving the desired ampere rating; and no fuse having a larger ampererating could then be inserted in that slot.

By varying thediameters and the orientations of the pins 214, 216, 218and 220 of the electric fuse 198, and by correspondingly varying thedimensions and orientations of the conductors 74, 80, 78 and 76, thepresent invention also can prevent over fusing. As a result, the presentinvention makes it possible to provide a highly desirable,rating-regulated, combination of electric fuse and fuseholder therefor.

The electric fuse 198 and the fuseholder 20 can be used successfully ina location where moisture and dripping water can be anticipated.Specifically, in such an installation, the nut 232 will hold the frontface of the gasket 118 in intimate engagement with the rear face of apanel, such as the panel indicated by dotted lines in FIG. 3; and thatintimate engagement will enable that gasket to seal the openings in thatpanel which accommodate the bosses 22 and 56. As a result, moisture ordripping water will be unable to pass through those openings. Also insuch an installation, the O-ring 72 will engage the exposed face of thesupport 210 of the electric fuse 198, and will coact with that exposedface to form a moisture-resistant and waterproof seal. The overallresult is that the electric fuse 198 and the fuseholder 20 can be usedsuccessfully in a location where moisture and dripping water can beanticipated.

The lamps 158 and 160, that are mounted within the recess 50 in the boss56, will preferably be neon lamps: because such lamps can be keptilluminated by the capacitance between the conductors 146 and 152 aftera fault has illuminated those lamps and then disappeared. However, inany installation where the anticipated circuit voltage is too low toilluminate a neon lamp, incandescent lamps will be substituted for theneon lamps 158 and 160 while those incandescent lamps will respond tothe fusing of the fusible element 226 and 228 to become illuminated, andwhile those incandescent lamps will remain illuminated as long as thefault which blew those fusible elements persists, those incandescentlamps will darken if that fault disappears. Consequently, the lamps 158and 160 will preferably be neon lam ps.

Whereas the drawing and accompanying description have shown anddescribed a preferred embodiment of the present invention it should beapparent to those skilled in the art that various changes may be made inthe form of the invention without affecting the scope thereof.

What we claim is:

1. A fuseholder which has a housing, a line terminal which is accessibleat one side of said housing, a load terminal which is accessible at asecond side of said housing, a second line terminal which is accessibleat said one side of said housing, a second load terminal which isaccessible at said second side of said housing, fuse-receiving terminalswhich are disposed within said housing and which are intermediate thefirst said line terminal and the first said load terminal and which arespaced away from said first said line terminal and also are spaced awayfrom said first said load terminal, and further fuse-receiving terminalswhich are disposed within said housing and which are intermediate saidsecond line terminal and said second load terminal and which are spacedaway from said second line terminal and also are spaced away from saidsecond load terminal, the accessibility of said line terminals at saidone side of said fuseholder and the accessibility of said load terminalsat said other side of said fuseholder minimizing the likelihood of anyarcing between one of said line terminals and one of said loadterminals, the spacing between the first said and said second lineterminals being substantially greater than the spacing between thefuse-receiving terminal connected to the first said line terminal andthe further fuse-receiving terminal connected to said second lineterminal, whereby the likelihood of any arcing between said lineterminals and any line conductors connected thereto is minimized, thespacing between the first said and said second load terminals beingsubstantially greater than the spacing between the fuse-receivingterminal connected to the first said load terminal and the furtherfuse-receiving terminal connected to said second load terminal, wherebythe likelihood of any arcing between said load terminals and any loadconductors connected thereto is minimized.

2. A fuseholder as claimed in claim 1 wherein said line terminals arethe exteriorly-located ends of conductors which are substantiallyL-shaped in configuration, wherein the feet of said L-shaped conductorsconfront and'extend toward each other and space the remaining portionsof said L-shaped conductors apart appreciable distances, wherein saidfeet of said L-shaped conductors are connected to two of saidfuse-receiving terminals, wherein said load terminals are theexteriorly-located ends of further conductors which are substantiallyL-shaped in configuration, wherein the feet of said further L-shapedconductors confront and extend toward each other and space the remainingportions of said further L-shaped conductorsapart appreciable distances,wherein said feet of said further L-shaped conductors are connected totwo of said fuse-receiving terminals, and wherein said feet of the firstsaid L-shaped conductors and of said further L-shaped conductors spacesaid remaining portions of said first said L- shaped conductors and ofsaid further L-shaped conductors further apart than the spacing betweenthe first said two fuse-receiving terminals.

3. An electric fuse which comprises a housing, a partition thatsubdivides said housing into two compartments and that projectsoutwardly beyond said compartments to constitute an aligning blade, aclosure for said housing which has a slot therein that telescopes oversaid aligning blade, said closure having spaced fuse terminals at oneside of said slot that have portions thereof disposable within one ofsaid compartments within said housing and having further spaced fuseterminals at the other side of said slot that have portions thereofdisposable within the other of said compartments within said housing, afusible element that spans the space between said portions of the firstsaid fuse terminals and that is disposable within the first saidcompartment within said housing, a second fusible element that spans thespace between said portions of said further fuse terminals and that isdisposable within said second compartment within said housing, saidpartition keeping any metallic vapors evolved during the fusing ofeither of said fusible elements from passing into the other compartmentwithin said housing, said aligning blade being disposable within a slotin a fuseholder to automatically align the first said fuse terminalswith fuse-receiving terminals therefor in said fuseholder and to alignsaid further fuse terminals with fuse-receiving terminals therefor insaid fuseholder.

4. An electric fuse as claimed in claim 3 wherein said housing has anoutwardly-extending annular recess therein adjacent the open end thereofand wherein the periphery of said closure is disposed within saidoutwardly extending annular recess, said partition having portionsthereof at the level of and merging smoothly into said outwardlyextending annular recess and underlying portions of said closure whichare between the ends of said slot and said periphery of said closure,and sealing material that seals the joint between said slot and saidaligning blade and seals the joint between said periphery of saidclosure and said outwardly-extending annular recess.

5. An electric fuse as claimed in claim 3 wherein arcextinguishingmaterial substantially fills said one compartment in said housing andengages and surrounds the first said fusible element, wherein furtherarcextinguishing material substantially fills said second compartment insaid housing and engages and surrounds said second fusible element,wherein sealing material closes an opening in said closure which is inregister with said one compartment in said housing and through which thefirst said arc-extinguishing material was introduced into said onecompartment, wherein sealing material closes a second opening in saidclosure which is in register with said second compartment and throughwhich said further arc-extinguishing material was introduced into saidsecond compartment, and wherein said closed openings in said closure aredisposed between said fuse terminals, whereby said fuse terminals willprotect the sealing material within said openings from nearby objects.

6. An electric fuse as claimed in claim 3 wherein said fuse terminalsproject outwardly beyond said closure and are engageable withfuse-receiving terminals in a fuseholder, and wherein said fuseterminals coact with said fuse-receiving terminals in said fuseholder tohold said closure immediately adjacent the surface of said fuseholder,whereby said fuseholder will act to protect said closure from injurywhenever said electric fuse is in assembled relation with saidfuseholder.

7. A fuseholder which has a plurality of fusereceiving terminalstherein, each of said fuse-receiving terminals having agenerally-cylindrical end with a tulip-type socket therein, having asmall-diameter end, and having an intermediate portion with a diametersmaller than the diameter of said generally cylindrical end but largerthan the diameter of said small-diameter end, connecting terminals thathave portions thereof disposed externally of said fuseholder and thathave portions thereof disposed within said fuseholder and that haveopenings in the internally disposed portions thereof, said openings insaid internally disposed portions of said connecting terminalsaccommodating and encircling said intermediate portions of saidfusereceiving terminals, and solder engaging and electrically bondingtogether said internally disposed portions of said connecting terminalsand said intermediate portions of said fuse-receiving terminals.

8. A fuseholder as claimed in claim 7 wherein a circuit board hasopenings which telescope over said small-diameter ends of saidfuse-receiving terminals, said circuit board having conductors thereonwhich are soldered to said small-diameter ends of said fusereceivingterminals.

9. A fuseholder as claimed in claim 7 wherein said connecting terminalsare generally L-sahped and have said openings therein, which receivesaid intermediate portions of said fuse-receiving terminals, in the feetthereof, said feet of said connecting terminals confronting andextending toward each other to displace the remaining portions of saidconducting terminals from each other by distances greater than thedistances between said fuse-receiving terminals.

10. A fuseholder as claimed in claim 7 wherein said connecting terminalshave offsets intermediate the ends thereof, said offsets disposing saidexternally disposed portions of said connecting terminals adjacent therear of said fuseholder and thereby displacing said externally disposedportions of said connecting terminals rearwardly of any panel with whichthe front of said fuseholder is associated.

11. A fuseholder which has a body of insulating material with aplurality of passages extending therethrough, fuse-receiving terminalsdisposed within said passages through said body of insulating materialand having the rear ends thereof projecting into a recess adjacent therear of said body of insulating material, a line terminal extending intosaid recess in said body of insulating material, a load terminalextending into said recess in said body of insulating material, acircuit board disposed within said recess in said body of insulatingmaterial, said line terminal having an opening therein which is disposedwithin said recess in said body of insulating material and whichencircles the rear end of one of said fuse-receiving terminals, aconductor on said circuit board which has an opening therein thatencircles said rear end of said one fuse-receiving terminal, said loadterminal having an opening therein which is disposed within said recessin said body of insulating material and which encircles the rear end ofanother of said fuse-receiving terminals, a second conductor on saidcircuit board which has a second opening therein that encircles saidrear end of said second fuse-receiving terminal, solder whichelectrically connects said line terminal and the first said conductor onsaid circuit board to said rear end of said one fuse-receiving terminal,and further solder which electrically connects said load terminal andsaid second connector on said circuit board to said rear end of saidsecond fuse-receiving terminal.

1. A fuseholder which has a housing, a line terminal which is accessibleat one side of said housing, a load terminal which is accessible at asecond side of said housing, a second line terminal which is accessibleat said one side of said housing, a second load terminal which isaccessible at said second side of said housing, fuse-receiving terminalswhich are disposed within said housing and which are intermediate thefirst said line terminal and the first said load terminal and which arespaced away from said first said line terminal and also are spaced awayfrom said first said load terminal, and further fuse-receiving terminalswhich are disposed within said housing and which are intermediate saidsecond line terminal aNd said second load terminal and which are spacedaway from said second line terminal and also are spaced away from saidsecond load terminal, the accessibility of said line terminals at saidone side of said fuseholder and the accessibility of said load terminalsat said other side of said fuseholder minimizing the likelihood of anyarcing between one of said line terminals and one of said loadterminals, the spacing between the first said and said second lineterminals being substantially greater than the spacing between thefuse-receiving terminal connected to the first said line terminal andthe further fuse-receiving terminal connected to said second lineterminal, whereby the likelihood of any arcing between said lineterminals and any line conductors connected thereto is minimized, thespacing between the first said and said second load terminals beingsubstantially greater than the spacing between the fuse-receivingterminal connected to the first said load terminal and the furtherfuse-receiving terminal connected to said second load terminal, wherebythe likelihood of any arcing between said load terminals and any loadconductors connected thereto is minimized.
 2. A fuseholder as claimed inclaim 1 wherein said line terminals are the exteriorly-located ends ofconductors which are substantially L-shaped in configuration, whereinthe feet of said L-shaped conductors confront and extend toward eachother and space the remaining portions of said L-shaped conductors apartappreciable distances, wherein said feet of said L-shaped conductors areconnected to two of said fuse-receiving terminals, wherein said loadterminals are the exteriorly-located ends of further conductors whichare substantially L-shaped in configuration, wherein the feet of saidfurther L-shaped conductors confront and extend toward each other andspace the remaining portions of said further L-shaped conductors apartappreciable distances, wherein said feet of said further L-shapedconductors are connected to two of said fuse-receiving terminals, andwherein said feet of the first said L-shaped conductors and of saidfurther L-shaped conductors space said remaining portions of said firstsaid L-shaped conductors and of said further L-shaped conductors furtherapart than the spacing between the first said two fuse-receivingterminals.
 3. An electric fuse which comprises a housing, a partitionthat subdivides said housing into two compartments and that projectsoutwardly beyond said compartments to constitute an aligning blade, aclosure for said housing which has a slot therein that telescopes oversaid aligning blade, said closure having spaced fuse terminals at oneside of said slot that have portions thereof disposable within one ofsaid compartments within said housing and having further spaced fuseterminals at the other side of said slot that have portions thereofdisposable within the other of said compartments within said housing, afusible element that spans the space between said portions of the firstsaid fuse terminals and that is disposable within the first saidcompartment within said housing, a second fusible element that spans thespace between said portions of said further fuse terminals and that isdisposable within said second compartment within said housing, saidpartition keeping any metallic vapors evolved during the fusing ofeither of said fusible elements from passing into the other compartmentwithin said housing, said aligning blade being disposable within a slotin a fuseholder to automatically align the first said fuse terminalswith fuse-receiving terminals therefor in said fuseholder and to alignsaid further fuse terminals with fuse-receiving terminals therefor insaid fuseholder.
 4. An electric fuse as claimed in claim 3 wherein saidhousing has an outwardly-extending annular recess therein adjacent theopen end thereof and wherein the periphery of said closure is disposedwithin said outwardly extending annular recess, said partition Havingportions thereof at the level of and merging smoothly into saidoutwardly extending annular recess and underlying portions of saidclosure which are between the ends of said slot and said periphery ofsaid closure, and sealing material that seals the joint between saidslot and said aligning blade and seals the joint between said peripheryof said closure and said outwardly-extending annular recess.
 5. Anelectric fuse as claimed in claim 3 wherein arc-extinguishing materialsubstantially fills said one compartment in said housing and engages andsurrounds the first said fusible element, wherein furtherarc-extinguishing material substantially fills said second compartmentin said housing and engages and surrounds said second fusible element,wherein sealing material closes an opening in said closure which is inregister with said one compartment in said housing and through which thefirst said arc-extinguishing material was introduced into said onecompartment, wherein sealing material closes a second opening in saidclosure which is in register with said second compartment and throughwhich said further arc-extinguishing material was introduced into saidsecond compartment, and wherein said closed openings in said closure aredisposed between said fuse terminals, whereby said fuse terminals willprotect the sealing material within said openings from nearby objects.6. An electric fuse as claimed in claim 3 wherein said fuse terminalsproject outwardly beyond said closure and are engageable withfuse-receiving terminals in a fuseholder, and wherein said fuseterminals coact with said fuse-receiving terminals in said fuseholder tohold said closure immediately adjacent the surface of said fuseholder,whereby said fuseholder will act to protect said closure from injurywhenever said electric fuse is in assembled relation with saidfuseholder.
 7. A fuseholder which has a plurality of fuse-receivingterminals therein, each of said fuse-receiving terminals having agenerally-cylindrical end with a tulip-type socket therein, having asmall-diameter end, and having an intermediate portion with a diametersmaller than the diameter of said generally cylindrical end but largerthan the diameter of said small-diameter end, connecting terminals thathave portions thereof disposed externally of said fuseholder and thathave portions thereof disposed within said fuseholder and that haveopenings in the internally disposed portions thereof, said openings insaid internally disposed portions of said connecting terminalsaccommodating and encircling said intermediate portions of saidfuse-receiving terminals, and solder engaging and electrically bondingtogether said internally disposed portions of said connecting terminalsand said intermediate portions of said fuse-receiving terminals.
 8. Afuseholder as claimed in claim 7 wherein a circuit board has openingswhich telescope over said small-diameter ends of said fuse-receivingterminals, said circuit board having conductors thereon which aresoldered to said small-diameter ends of said fuse-receiving terminals.9. A fuseholder as claimed in claim 7 wherein said connecting terminalsare generally L-sahped and have said openings therein, which receivesaid intermediate portions of said fuse-receiving terminals, in the feetthereof, said feet of said connecting terminals confronting andextending toward each other to displace the remaining portions of saidconducting terminals from each other by distances greater than thedistances between said fuse-receiving terminals.
 10. A fuseholder asclaimed in claim 7 wherein said connecting terminals have offsetsintermediate the ends thereof, said offsets disposing said externallydisposed portions of said connecting terminals adjacent the rear of saidfuseholder and thereby displacing said externally disposed portions ofsaid connecting terminals rearwardly of any panel with which the frontof said fuseholder is associated.
 11. A fuseholder which has a body ofiNsulating material with a plurality of passages extending therethrough,fuse-receiving terminals disposed within said passages through said bodyof insulating material and having the rear ends thereof projecting intoa recess adjacent the rear of said body of insulating material, a lineterminal extending into said recess in said body of insulating material,a load terminal extending into said recess in said body of insulatingmaterial, a circuit board disposed within said recess in said body ofinsulating material, said line terminal having an opening therein whichis disposed within said recess in said body of insulating material andwhich encircles the rear end of one of said fuse-receiving terminals, aconductor on said circuit board which has an opening therein thatencircles said rear end of said one fuse-receiving terminal, said loadterminal having an opening therein which is disposed within said recessin said body of insulating material and which encircles the rear end ofanother of said fuse-receiving terminals, a second conductor on saidcircuit board which has a second opening therein that encircles saidrear end of said second fuse-receiving terminal, solder whichelectrically connects said line terminal and the first said conductor onsaid circuit board to said rear end of said one fuse-receiving terminal,and further solder which electrically connects said load terminal andsaid second connector on said circuit board to said rear end of saidsecond fuse-receiving terminal.